Metabolic disorders

Nutrition plays a pivotal role in preventing metabolic disorders
post calving and through lactation. Metabolic disorders such as
ketosis, fatty liver syndrome, hypocalcaemia etc can have a
significant effect not only on a cow's lactation performance, but
also fertility performance. These types of problems tend to be
associated with higher yielding animals, however, all are
controllable by good feeding practice, both in lactation and during
the dry period.

Common disorders:

Acidosis

Incorrect diets or feeding can lead to overly rapid fermentation
in the rumen, which reduces the pH below the level at which the
microbes are most active. This slows down forage digestion and
reduces both feed intake and cud chewing which makes the problem
worse by limiting the buffering effect of salivation.

Hypocalcaemia (Milk Fever)

The huge demand for calcium produced by the onset of milk
production can cause blood calcium levels to drop sharply,
precipitating milk fever either before or at calving. Even
though cows can mobilise skeletal calcium, the process is slow and
made worse by the demands of high yielding stock.

Hypomagnesaemia(Grass Staggers)

Cows only have a limited body reserve of magnesium and can only
absorb a small proportion of the mineral in their diet, therefore
grass staggers is easily precipitated by a fall in dietary
magnesium. The risk is highest early in the grazing season given
the lushness and low mineral content of spring grass, particularly
if it is rich in nitrogen and potash. Similarly, later season grass
in autumn can give rise to low mineral content.

Ketosis(Acetonaemia)

Often charaterised by a pear drop like smell on the breath,
ketosis commonly occurs as the result of a severe early lactation
energy gap. The mobilization of large amounts of body fat in the
liver, in an attempt to bridge the shortfall, can lead to toxic
levels of ketones accumulating in the blood, milk and urine. This
results in a loss of appetite and a marked fall in milk yield.

Factsheet 1 within
feeding+ has more detailed information on
metabolic disorders and how to address them.